Performing precision operations with instruments requires that the instruments are accurately positioned with respect to whatever the operations are being performed on. Transcranial magnetic stimulation, TMS, for example, is used to magnetically stimulate a small area inside a person's brain which requires that a magnetic coil used be positioned accurately, for shorter or longer periods of time, along the outside of the person's head. Similarly, for example, radiation therapy greatly benefits from aiming radiation patterns accurately at malignant cells to avoid damaging healthy tissue.
Using TMS as an example, a patient may be instructed to maintain his head immobile while a stimulating coil is moved along the outer surface of his head. If the coil is held accurately and reliably at the correct location, the stimulating effect can be aimed at a desired location inside the brain. On the other hand if the coil is inaccurately placed or accidentally moves, results of TMS are expected to be adversely affected.
TMS may be used, for example, to locate a position representing a certain muscle for defining a person's motor threshold position, to facilitate rehabilitation following a stroke or to treat depression, for example. Radiation therapy may be used to kill malignant cells. Using a manual placement technique, a treatment position on the patient's head or a position used to find a treatment position, such as the patient's motor threshold position, MTP, may be determined by moving a TMS coil near a predicted area determined by patient anatomical landmarks until the desired motor response is achieved.
US2009227830 describes an apparatus for positioning a medical instrument, such as a TMS coil, with respect to a patient.